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Questions about using a Kit-281 as a center


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5 replies to this topic

#1 of 6 OFFLINE   Todd Stout

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Posted October 23 2005 - 11:22 AM

Hello all, I currently have 3 Adire Audio Kit-281 and 2 Kit-81 speaker kits that I have had for about 3 years now. I intend on building ported cabinets for the left and right 281s and a sealed cabinet for the center 281. I'm finally getting ready to build them now but I have been dragging my feet a bit the past few weeks because of what I have been reading about using an MTM speaker for a center channel. Is "lobing" a big problem with the 281 when it's placed on its side and used as a center? There seems to be two camps on this subject with half saying all MTM speakers exhibit lobing while the other camp argues that it isn't much of a problem. If this is a big issue, is it too late to obtain an AV-5 along with the necessary crossover components to turn my third 281 into a Kit-LCC? If I can't get my hands on an AV-5, perhaps another midrange could be added along with a custom crossover to turn my 281 into something resembling an LCC. Is that something that would be worth the effort? How heavy is a sealed 281? I have been trying to figure out where to place it around my Hitachi 46F500 TV and I am guessing that it will be way too heavy to place on top of my TV. I guess I could put it on a stand of some sort in front of the TV or perhaps on a shelf above it. Thanks guys.

#2 of 6 OFFLINE   Kyle Richardson

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Posted October 24 2005 - 02:02 AM

Todd, I use the exact same set up for my theater as you are proposing (vented 281's for mains, sealed 281 for center, and 81's for surround duty). The sealed 281 works perfectly fine for a center channel unless you are quite far off axis and that probably isnt an issue with 85-90% of most rooms. The speaker is quite heavy but I place mine directly on top of my 65" Toshiba RPTV and it's been fine and has a longer span than your 46" model will have so I'd think you would be fine too. Go for it and you'll be happy!
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#3 of 6 OFFLINE   Danny Richie

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Posted October 24 2005 - 04:17 AM

Todd, what happens when you lay an MTM speaker on its side, then move off axis, you get into a situation where one woofer is further away (in time) than the other. Once it is delayed enough to be out of phase with the other woofer it cancels it and causes a dip in the response.

How far off axis you can get without this happening is directly a result of the acoustic centers of the woofers.

The closer they are together the less the problem and the greater the coverage area.

We offer a side laying MTM center channel as well. See it as an example.

Posted Image

Acoustic centers are 9.5" apart on the woofers.

With this design you have good coverage out to 20 degrees off axis with a slight but acceptable dip beginning at 25 degrees off axis.

If you sit further off axis than this you will experience a dip in response. If your seating is going to include areas further off axis than 25 degrees then I would not recommend that model.

If acoustic centers were to be pulled out further it would be worse. 12.5" center to centers might begin to show dips in the off axis as soon as 18 degrees or less.

This is not much coverage area.

I really wouldn't recommend an MTM on its side as a center with acoustic centers any further apart than about 10" or so unless you plan to sit right in front of it all the time.

#4 of 6 OFFLINE   Patrick D

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Posted October 24 2005 - 12:27 PM

This is kind of OT but I never understood why it was bad to lay an MT speaker on its side either... I tried it with mine and didn't like it as much.

#5 of 6 OFFLINE   Kyle Richardson

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Posted October 25 2005 - 01:37 AM

Exactly as Danny mentioned, the further off axis you go the worse the response will be from an MTM on its side but by the time you reach 25 degrees you are introducing so many other detrimental effects that the dip in response isn't as large of an issue as many have made it IMO. The further you move off center the worse your stereo response (balance) will be, your picture from an RPTV will likely start to change, room response will change (likely you are getting closer to a wall), etc. That is why I said it isn't an issue in most rooms because most seating setups fall under 20-25 degrees off axis.
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#6 of 6 OFFLINE   Todd Stout

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Posted October 25 2005 - 02:02 PM

I think my total viewing area might be a little wider than 25 degrees. My viewing position is directly in front of the TV but there are some fringe areas of the couches that might be a bit outside of that 25 degree arc. In any case, I imagine that I'll still be in better shape with the Adire speakers than with what I have now. Another thing that keeps me dragging my feet is the really low price of the JBL Northridge speakers at several online sites right now. I can get a pair of E90s, an EC35, and a pair of E30s for $700 with free shipping right now. I have heard the E60 and E80 and think they are both rather nice sounding speakers. I don't think the JBLs are quite as nice as the Energy C9s that I had auditioned at the local Good Guys a few months ago but certainly nice for the price. After reading several reviews (including the one in AudioXpress that inspired me to buy the Adire kits in the first place) I would imagine that the Kit-281 will sound better than the JBL E90. I am hoping that the Kit-281 has that same smooth sound that the Energy C9 or even some of the newer JBL Northridge speakers have. In contrast, I'm not a big fan of the Klipsch Reference series. I auditioned the RF-7's a couple of years ago and was very impressed with the imaging but something about them turned me off. My dad now has a set of the RF-7s along with the matching center and surrounds and while I think his system sounds okay, I wouldn't go out and buy a set for myself. Any comments on what the 281 sounds similar to? I really do plan on building my Adire kits, I just keep coming up with reasons to put it off a bit longer. I just need to get my ass in gear and do it!